Hypersensitivity to Platanus acerifolia pollen: detection of the allergenic fractions

Background: Although the small clinical relevance of trees in pollinosis, as compared to other plants, is well known, in Barcelona the role of the plane tree (Platanus acerifolia), the most numerous tree species in the city, is significant. We have carried our a clinical and immunological study of the hypersensitivity to the pollen of Platanus acerifolia (hybrida) in Barcelona in order to assess its prevalence and to determine the allergenic fractions in the pollen extract used in the study. Methods: A total of 3450 consecutive medical records from our institution were reviewed. The diagnostic work-up consisted of skin prick tests to common airborne allergens including P. acerifolia pollen, specific IgE quantitation, and nasal challenge tests. Results: Twenty-four patients clinically sensitized to P. acerifolia pollen were found. This group accounted for 3.6% of the total number of pollinosis detected. By means of sodium dodecylsulfatepolyacrylamide gel electrophoresis (SDS-PAGE) several different protein fractions were identified, mostly of 10, 14, 25 and 40 kDa molecular mass. The fractions most frequently fixing specific IgE were those of 5, 13, 23, 40, 43 and 66 kDa molecular mass. The isoelectric focusing studies detected major bands in the pI range between 4.5 and 7.0; the specific IgE was most frequently fixed by the pI 4.0 and 9.0 bands. Conclusions: A 3.6% prevalence of clinical sensitization to Platanus acerifolia in respect to the total number of pollinosis was documented in the city of Barcelona over a one-year period. The high percentage of cases with monosensitization to this pollen should be noted, as well as the great heterogeneity of the allergenic fractions detected.